There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

What month of the year has 28 days?

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

Can you solve this amazing hard number series problem?
7, 8, 10, 12, 16, 18 ?

John can fit six large chocolate boxes or nine small chocolate boxes into a carton. How many cartons will he require to put sixty-six chocolate boxes into?

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?

Which number comes next in the number series?

2, 9, 30, 93, ?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

Why 1729 is a magic number? Answer Logically.